Where can I find definitions for the real time PID that I am reading on my scanner connected at the OBD II port of my SLK320?

Thanks,

George

 

Hi,

Not sure what you are trying to do?

OBD is a standard and most scanners turn the data stream directly into DTC's with a lookup facility or alternatively display live streams with appropriate values and definitions as graphs, meters etc.

Seems like you are trying to write the scanner software. Raw data is in hexadecimal format.

If you mean where can you get DTC definitions from just Google Diagnostic Trouble Code or even DTC or OBDII etc.

However some engine codes are proprietary even within the structure of OBDII. i.e. Codes starting P1xxx are potentially unique to a specific manufacturer and closely guarded by that manufacturer. However P0xxx codes have common definitions.

Body (SRS, ABS, ESP etc codes do not yet have to comply with common OBDII style definitions and remain proprietary although they work in exactly the same way and much data / information is shared between the different on board networks.

However forums like this have good intelligence if you want to know the definition of a specific code.

Stuart..

 

Stuart

Thank you for your response.

I understand the DTC aspect of the scanner/OBD II function and have an exhaustive table of both the generic and vehicle specific trouble codes for my vehicle. In this case, my car scans successfully but has notrouble codes.

My scanneralso displays realtime parametric data for around 30sensors/measurements such as coolant temperature, engine RPM, vehicle speed, various voltages, etc. For many of these, it isobvious what is being measured (like coolant temperature in degrees F) and what the value means but on some of the 30 or so parameters being displayed, it is not clear what they are. Given my lack of fuel pressure I am particularly interested in "Fuel1" and "Fuel2". The manual for my Actron scanner (CP9145) calls this function Parameter Identification Data or PID. This is a different function from the process of extracting trouble codes.

Do you know where I can get definitions for these 30 or so realtime parameters so that I can see what is being measured?

Thanks,

George

 

Hi,

Yes I am familar with the live data feed. I have an AuterraDyno Scan which is a most useful bit ofkit because it is so compact, inexpensive and runs on a standard Palm PDA...so I have my scanner with me all the time! It shows values as readings, gauges, graphs, exportetc and can show multiple feeds at the same time.

What I don't understand is why each feed is not labelled or are they and you are asking what Fuel 1 / 2 is?

If you have a feed with the title Fuel 1 and 2 I suspect this is what is know as STFT (Short Term Fuel Trim) and LTFT (Long Term FT)

This value shows you what correction is being applied to base line fuelling and is useful if you suspect MAF Mass AirFlow proiblems.

I'm not aware that MB offer a fuel pressure live feed (which needs to be in the vehicle EMS software) hence the schraeder valve on the fuel rail. In addition I'm not aware of a fuel pressure sensor anywhere in the system.

Does this help.

Stuart

 

Stuart

Yes this helps. Do you know where I can go to get definitions for all of my real time data feeds?

What does the value of "open" mean for Fuel1 and Fuel2?

Thanks,

George

 

Need to see the data in context.

Open usually means ...no connection, open (vented) e.g. to atmosphere, valve open etc.

PM me with your email so that we can exchange images / files.

The live data feeds are different on different makes and model/year dependent upon on what the manufacturer decides they require for dioagnostic purposes.

Connection to the data bus will advise what is available as a header to each feed of data. There is no set format, protocol etc. which is why most data stream equipment (other than OBDII codes) is proprietary to the manufacturer and hence very expensive because of its commercial potential.

Lots of equipment can access the data stream but deciphering it is another matter. Doesn't your scanner have a Parameter Select function. This lists what is available for you to select from.

Typical Parameters are:

Abs Throttle Position
Absolute Load Value
Air Flow Rate from MAF
Ambient
Baro Pressure
Calc Load Value
Cat Temp Sensor 1
Ditto X4
Commanded EGR
Commanded Equivalence Value
Coolant temp
RPM
Evap System Pressure
Fuel level
FUEL RAIL PRESSURE
Fuel Rail Pressure (Gauge)
Fuel Rail Pressure Relative to Atmos
Ignition Timing
Intake Temp
Intake Manifold Pressure
LTFT B1
LTFT B2
Minutes run with MIL (CEL) ON
O2 B1 Sensor1
O2 B1 Sensor1 Wide Range (r)
O2 B1 Sensor1 Wide Range (v)
Ditto for other Banks and sensors
etc etc

BUT many of these will not be available on your specific data stream.

Firstly the fuel map algorythm need to have appropriate sensor feeds and secondly a need to export the data especially calculated values.

I'll take a screen shot of the list or type it up for you off my own equipment when connected to my SLK320 but I don't unsderstand what you are trying to achieve.

I assure you fuel rail pressure is NOT one of the available feeds on SLK320! Could be on SLK 230 Kompressor due to supercharger.

Stuart.





Stuart

 

Stuart

I will be back down to the car this weekend at which time I will extract the parameters that I get via the live data feed and list them and their values.

My objective is to understand them all so that I can benefit from what the data is telling me and this and any future problems.

How do you find using a PC/Palmtop based code reader vs a handheld dedicated box like I have?

Thanks,

George

 

PC's a too bulky!
Everybody who sees my Palm including Ford (Land Rover) for whom I use to work and Mercedes (local dealership) are amazed at the convenience of the Palm.
The fact that it does a lot of what Star does and in addition supports 0-60 acceleration time (including gearchange points etc) testing etc. Need I say more.
Totally robust software!!

Only drawback is that as of present it only supports Engine/Trans functionality and not Body/SRS etc.
However. Auterrta tell me they are working on this but since i have been waiting 3 years they must be finding it difficult.

Super value. Was on special promo at 150 USD when I got it. It supports all protocols inc CAN so is universal. has its own "click on code" type data database when and if a code is displayed and if not you can use a lookup window.

Only other thing I would like is a wireless connection to the OBD port but a long lead isn't actually a problem.

Go Auterra and have a look at the functionality and screens if you want to know more.

Stuart.